karol_abratkiewicz:
but I don't see any startListening or stopListening functions.
That's because it does not need them - that is the beauty of the idea. All that complexity is handled automatically by the nRF24.
The code you posted (please use the code button </> for posting code) is designed to work with the example in the SimpleRxAckPayload program.
I suggest you start by getting the pair of SimpleRxAckPayload and SimpleTxAckPayload to work and so you understand what is happening. Then the multi- version will make more sense.
...R